Method of forming vertical bores through the ground



June 23, 1970 YASUO ITAMI ETAL v3,516,255

METHOD OF FORMING VERTICAL BORES THROUGH THE GROUND Filed Jan. 2, 1969 EIG.1

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I L AM C VZ TL INVENTORS ATTORNEY United States Patent 3,516,256 METHOD OF FORMING VERTICAL BORES THROUGH THE GROUND Yasuo Itami, Tokyo, and Akira Takahashi, Odate-slli,

Japan, assignors to Japan Development and Construction C0., Ltd., Tokyo, Japan, a corporation of Japan Filed Jan. 2, 1969, Ser. No. 788,589 Int. Cl. E21d 5/00 US. Cl. 61-41 4 Claims ABSTRACT OF THE DISCLOSURE A vertical bore of a relatively large diameter is formed through the ground by a method comprising the steps of successively forming a plurality of closely adjacent vertical. piles of reenforced concrete until a cylindrical peripheral wall structure is obtained, removing, the soil inside the peripheral wall structure to a depth smaller than that thereof, fabricating a first inside ring around the inner periphery of the peripheral wall structure at said predetermined depth and alternately effecting digging and fabrication of succeeding inner rings to the bottom of the peripheral wall structure.

BACKGROUND OF THE INVENTION This invention relates to a method of forming a vertical bore through the ground and more particularly to a method of safely digging a bore of a relatively large diameter such as a bore utilised to dig ore.

It is impossible to form such a bore of relatively large diameter by utilizing a boring drill. According to one prior method, a number of long piles were driven into the ground to form a peripheral wall, and the soil surrounded by the peripheral wall was then removed to form a bore. However, where the ground is hard it is difficult or impossible to drive piles into the ground.

SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide a new and improved method of forming a vertical bore of a relatively large diameter through the ground.

According to this invention, a deep vertical opening of relatively small diameter is formed through the ground. Such a small opening can be readily bored by means of conventional drilling operation even when the ground is hard. Then a pile is fabricated in the opening by means of steel reenforced concrete. A number of such concrete piles are successively formed in closely adjacent relationship until a cylindrical peripheral wall structure is obtained. Then the soil inside the cylindrical peripheral wall structure is removed to a predetermined depth smaller than that of the peripheral Wall structure. A first inside ring of concrete is fabricated around the inner periphery of the peripheral wall structure at said predetermined depth. Thereafter, digging of the soil and fabrication of succeeding rings are alternately effected to the bottom of the peripheral wall structure. Successive inside rings serve to reenforce the peripheral wall structure against the pressure of soil and these rings may be contiguous or spaced apart each other. Where the depth of the bore to be formed is deep, a similar combination structure comprising an additional cylindrical peripheral wall and a number of inside rings may be formed within and beneath the first mentioned cylindrical peripheral wall structure.

BRIEF DESCRIPTION OF THE DRAWING This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawing in which:

3,516,256 Patented June 23, 1970 ice DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the accompanying drawing a deep vertical opening of relatively small diameter is formed by using a conventional boring drill. Then a pile 1 is fabricated in the opening by means of steel reenforced concrete. A large number of such concrete piles 1, 1 are successively fabricated in closely adjacent relationship until a cylindrical peripheral wall structure 2 having a diameter of approximately 50 meters is obtained. Where it is desired to reenforce the peripheral wall structure the heads of respective piles may be rigidly interconnected by a peripheral ring 3. After constructing the peripheral wall structure to a predetermined depth, the soil in the wall structure is removed by using a suitable digging machine. However, instead of digging to the lower end of the peripheral wall structure, digging is limited to a certain depth, for example one half of the depth of the peripheral wall structure, where piles 1 and 1 can well withstand against the soil pressure. At the bottom of the bore thus formed, a first inside ring 4 of concrete is fabricated to reenforce the peripheral wall structure.

Where the first inside ring 4 is massive, an annular groove corresponding to ring 4 is digged adjacent the inner periphery of the peripheral wall structure, then the first inside ring 4 is fabricated and finally the soil surrounded by the ring 4 is digged. In the same manner, the second, third, fourth inside rings 4', 4" may be successively fabricated as shown in FIGS. 2 and 3. In the embodiment shown in FIG. 3 respective inside rings 4, 4', 4" are contiguous with each other whereas in the embodiment shown in FIG. 3 adjacent inner rings are spaced apart by rings of soil that have not been removed.

In this manner, according to this invention since fabrication of successive inside rings 4, 4', 4" and digging of the soil inside the peripheral wall structure are performed alternately until a desired depth is reached where an ore bed 5, for example is buried so that the peripheral wall structure is maintained always in safe condition. Where the depth of the ore bed is extremely large, a similar combination of peripheral wall comprising a plurality of closely adjacent piles and a plurality of inside rings may be constructed inside and beneath the structure shown in the drawing. As shown in FIG. 1 suitable ladders 6 and 6' may be set up for the convenience to workmen.

Thus according to the novel method a deep vertical bore can be formed readily through the ground under safe condition because respectively piles of the peripheral wall structure are successively formed by boring operations and the peripheral wall structure is successively reenforced as the digging operation proceeds. While the invention has been described in terms of a preferred embodiment to dig a bore for digging ore at a deep depth it should be understood that the invention can equally be applied to other fields.

What is claimed is:

1. A method of forming a vertical bore through the ground comprising the steps of successively forming a plurality of closely adjacent piles by first forming elongated openings and then fabricating said piles in said openings with steel reenforced concrete until a cylindrical peripheral wall structure is obtained, removing the soil inside the cylindrical peripheral wall structure to a predetermined depth smaller than that of said peripheral wall peripheray of said peripheral wall structure at said predetermined depth, digging the soil inside and beneath said first inside ring to a second predetermined depth, fabricating a second inside ring around the inner periphery of said peripheral wall structure at said second predetermined depth, thereafter alternately effecting fabrication of a third, a fourth and so on inside rings and digging of the soil in said peripheral wall structure.

2. The method according to claim 1 wherein said plurality of inside rings are contiguous with each other.

3. The method according to claim 1 wherein said plurality of inside rings are spaced apart by the soil that has not been removed.

4. The method according to claim 1 wherein after fabricating a first structure comprising said cylindrical peripheral wall structure and said plurality of inside rings,

, 4 a second structure similiar to said first structure is fabbricated within and beneath the same.

References Cited UNITED STATES 1 PATENTS 460,545 9/1891 Wolif 61-40 543,230 7/1895 Dubbs 6140 1,009,312 11/1911 Jackson 61--41 1,398,221 11/1921 Boardman 6141X FOREIGN PATENTS 908,993 10/1962 Great Britain.

129,066 3/1902 Germany.

290,361 11/1931 Italy.

DENNIS L. TAYLOR, Primary Examiner 

